Ethanol can be produced from grain-based feedstocks (e.g. corn, sorghum/milo, barley, wheat, etc.), from sugar (e.g. from sugar cane, sugar beets, etc.), and from biomass (e.g. from lignocellulosic feedstocks such as switchgrass, corn cobs and stover, wood, other plant material, or algae).
Biomass comprises plant matter that can be suitable for direct use as a fuel/energy source or as a feedstock for processing into another bioproduct (e.g., a biofuel such as cellulosic ethanol) produced at a biorefinery (such as an ethanol plant). Biomass may comprise, for example, corn cobs and stover (e.g., stalks and leaves) made available during or after harvesting of the corn kernels, fiber from the corn kernel, switchgrass, farm or agricultural residue, wood chips or other wood waste, algae, and other plant matter. In order to be used or processed, biomass is harvested and collected from the field and transported to the location where it is to be used or processed. An example of a way to efficiently collect and transport biomass is biomass bales. Biomass may be collected and baled during or after grain harvest.
In a conventional ethanol plant producing ethanol from corn, ethanol is produced from starch. In contrast, in a biorefinery configured to produce ethanol from biomass such as cellulosic feedstocks, ethanol is produced from lignocellulosic material (e.g. cellulose and/or hemi-cellulose). The biomass is prepared so that sugars in the cellulosic material (such as glucose from the cellulose and xylose from the hemi-cellulose) can be accessed and fermented into a fermentation product that comprises ethanol (among other things). The fermentation product is then sent to the distillation system where the ethanol is recovered by distillation and dehydration. Other bioproducts such as lignin and organic acids may also be recovered as co-products. Determination of how to more efficiently prepare and treat the biomass for production into ethanol will depend upon (among other things) the form and type or composition of the biomass.
For example, the moisture content of the biomass bales can vary considerably (e.g., from less than 20 percent to more than 40 percent) based on harvest conditions, harvest timing, storage conditions, and the like. Knowledge of the moisture content of the bales brought to the facility directly affects the amount of water introduced into the ethanol production process. Likewise, knowing the moisture content of the bales at the time of purchase is beneficial because the price of the bales is usually set on a dry matter basis. It would also be beneficial for farmers to be able to monitor the moisture content of their bales in storage.
In addition to use in a cellulosic ethanol production facility, biomass may be utilized in a wide variety of downstream applications, such as feedstock for farm animals, fertilizer and composite materials, ground cover, and the like. In each of these applications, determining the moisture content of the biomass may be particularly important for assessing quality and/or pricing for the biomass product.
Many assays exist for determining moisture content of plant materials, often comprising measuring weight loss during drying in an oven, for example. Measuring moisture content using an oven usually consumes considerable time and is not a portable method. Other methods include, for example, Near Infrared Spectroscopy (NIR), which requires expensive and sensitive equipment and is also not very suitable for field use.